1. STOICHIOMETRY
Chapter 9: Pages

2. Cooking with Chemistry
The Balanced Equation!
If we want to know how to make a product, how do we know the “recipe” for making that product?

3. Two Types of Stoichiometry
Composition Stoichiometry – the conversions between mass, moles, particles, and liters of a substance.
Reaction Stoichiometry – the conversions between reactants and products in a chemical reaction.

4. Concept Base You must know how to Balance equations
Calculate molar mass for any substance
Convert moles into grams using molar mass
Convert moles into particles using 6.02 x 1023
Interpret the meaning of a balanced equation

5. Interpreting Equations
NO!
2C(s) O2 ® 2CO(g)
2 mole C + 1 mole O2 ® 2 mole CO
2 atoms C + 1 molecule O2 ® 2 molecules CO
2 g C g O ® 2 g CO NO!!!

6. Coefficients Coefficients represent mole ratios particle ratios
(and even the ratio of Liters for some gases as we will see later)
BUT NEVER
mass ratios.

7. 2C(s) + O2(g) ® 2CO(g)
Q1: How many moles of CO are produced from the reaction of 2 moles of C with an excess of O2?
A1: 2 moles CO
Q2: How many moles of CO are produced from the reaction of 1 mole of C with an excess of O2?
A2: 1 mole CO

8. 2C(s) + O2(g) ® 2CO(g) A3: 3.56 mol CO
Q3: How many moles of CO are produced from the reaction of 3.56 mol of C with an excess of O2?
A3: 3.56 mol CO
Q4: How many moles of CO are produced from the reaction of 2.50 mol of O2 with an excess of C?
A4:

9. 2C(s) + O2(g) ® 2CO(g)
Q5: How many grams of C are used in the reaction to produce 3.00 moles of CO?
A5: 2 2
= 36.0 g C

10. 2C(s) + O2(g) ® 2CO(g)
Q6: How many grams of C are used in the reaction to produce 9.8 grams of CO?
A6:
= 4.2 g C

11. 2C(s) + O2(g) ® 2CO(g)
Q7:How many grams of O2 are used in the reaction to produce 1.24 x 1024 molecules of CO?
molecules CO ®
molecules CO ® mol CO
molecules CO ® mol CO ® mol O2
molecules CO ® mol CO ® mol O2 ® g O2
= 33.0 g O2

12. 2C(s) + O2(g) ® 2CO(g)
Q8: How many molecules of O2 are used in the reaction to produce 3.4 moles of CO?
A8: 1.0 x 1024 molecules O2
Q9: How many atoms of C are used in the reaction to combine with 3.6 g of O2?
A9: 3.8 x 1022 atoms C

13. You Try It.
Do the Stoichiometry Worksheet #1.